1. Field of the Invention
This invention relates to components for robot arms and has particular application to robot arms used for cutting or drilling a work piece. Specifically, the invention provides an improvement to teach and repeat probes for robot arms.
2. Discussion of Prior Art
In order to program a robot arm to perform a specified cutting or drilling operation on a work-piece it is necessary to initially perform some type of teaching process. The "teach and repeat" method is one such process.
When teaching a robot arm how to perform a cutting process, for example, one known teach and repeat method involves replacing the cutting tool with a probe and moving the robot arm with the probe attached around the contours of a test-piece. The test-piece has the same shape as the finished component which is to be cut out of the work-piece. The robot arm is driven manually by an operator and is taught from one point to the next around the profile of the piece. Points chosen by the operator are programmed into the robot arm manually. Thus when the probe is replaced by the cutting tool, the robot arm automatically cuts the desired shape by moving between consecutive program points.
The probe and test-piece alignment must be done by visual inspection with the occasional assistance of a feeler gauge. This method has the disadvantage that viewing often has to be done at very awkward angles. When many points need to be programmed into the robot arm, this procedure is very laborious.
Known teach and repeat probes are of a solid, rigid design. They have a larger diameter than the cutting tool so that they are not prone to bending when in use. Any bending of the probe, would of course give rise to inaccuracies in the program points. Having an oversized probe is a disadvantage because in order to compensate for the larger diameter of the probe, the test-piece must be made correspondingly smaller than the desired finished article.